How Was Yumi's Cells Created? Donggeon Lee, Korean Expressions & the Cell Idea

Spoiler level: None beyond the basic premise. This article explores the creation of Yumi’s Cells through interviews with its original artist, Donggeon Lee. It does not reveal major relationship developments or the ending.

A tiny character inside your head announces that it has an opinion. Another disagrees. A third is more concerned about something completely unrelated.

Suddenly, a small everyday decision becomes a rather lively meeting.

That’s the playful storytelling idea behind Yumi’s Cells, the Korean webtoon created by Donggeon Lee (이동건).

The concept feels so natural that it might be tempting to assume the artist began with a grand plan for an imaginary world inside the human mind.

But interviews with Lee reveal a more down-to-earth creative background.

Before creating Yumi’s Cells, he had worked with stationery designs and small illustrated characters. He also found inspiration in familiar jokes about emotions and the different versions of ourselves that seem to make our decisions.

Those details help explain something important about the series.

The cells weren’t created simply to make Yumi’s emotions look cute. They gave the artist a flexible way to turn everyday thoughts, relationships, and difficult-to-explain feelings into visual storytelling.

And the ordinary nature of those experiences was part of the point.

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Who Created Yumi’s Cells?

Yumi’s Cells (유미의 세포들) was created by Korean webtoon artist Donggeon Lee (이동건), who is credited for the original comic’s writing and artwork.

It began publishing on Naver WEBTOON in April 2015.

The original Korean series is complete, with 512 episodes listed on its official page.

The official English WEBTOON edition is also marked completed.

The story follows Yumi, an ordinary woman whose thoughts and feelings appear as small characters living inside her mind.

Her outside life involves work, relationships, and everyday uncertainty. Inside her head, the cells react to those experiences in their own ways.

Lee’s webtoon didn’t originate as a prose novel that someone else later illustrated.

It was created for comics.

That distinction matters because the little characters, their expressions, and the contrast between Yumi’s outside and inside worlds are central to the original storytelling approach.

Before the Cells: From Stationery Designs to Webtoons

One of the most interesting facts about Lee’s creative background is that he worked with stationery before becoming known for webtoons.

In a 2023 interview published by Korea.net, Lee explained that he had operated a small stationery business and developed diary stickers under the name A Bittersweet Life.

He began creating comics to promote those designs.

That work eventually led into his career as a professional webtoon artist, with A Bittersweet Life becoming an early published comic.

It’s an unusual route into a field often associated with long-form illustration and serialized storytelling.

A small stationery character has to communicate an idea quickly.

There may be little room for elaborate detail, and the expression often needs to be recognizable at a glance.

Those practical qualities also make sense in a comic about personified feelings.

The reader should be able to identify a cell’s mood or concern without requiring an explanation every time it appears.

Where Did the Rounded Cell Designs Come From?

Lee connected his early drawing style directly to his stationery work.

In the Korea.net interview, he explained that the small, rounded character designs he used in that work helped shape the way he initially drew comics.

But he also recognized that storytelling required more expressive detail.

A decorative character and a character performing in a comic don’t have identical jobs.

A sticker can communicate a single emotion. A comic character may need to react, hesitate, argue, or change its expression across several panels.

Lee described gradually developing his drawing approach to make those emotional performances more effective.

That provides a useful way to understand the cells’ appearance.

Their simple shapes aren’t merely decorative. They allow emotions to become recognizable characters that can participate in a scene.

The visual simplicity makes the idea approachable; the characters’ expressions make it work as a story.

The Korean Expressions Behind the Cell Idea

The origin of the cells becomes even more interesting when Lee discusses everyday Korean speech.

In his 2023 interview, he recalled familiar joking expressions about romantic feelings and leaving unfinished work for a future version of oneself.

Rather than inventing a completely unfamiliar vocabulary, he was interested in expressions that already turn feelings or impulses into something almost person-like.

연애세포: When Your Romantic Feelings Have Gone Quiet

One example is 연애세포 (yeonae sepo).

연애 refers to dating or romantic relationships, while 세포 means cell.

In everyday Korean conversation, someone might jokingly say their dating cells have gone dormant after a long period without romantic interest.

It doesn’t mean anyone believes there’s a literal biological cell responsible for dating.

It’s a playful metaphor.

But imagine taking that metaphor seriously for the purposes of a comic.

What if the feeling really did have a character?

What if it could become excited, discouraged, or disagree with the other parts of someone’s inner life?

An ordinary joke suddenly offers a storytelling device.

This is an important distinction from the webtoon’s fictional Love Cell, or 사랑세포.

The everyday phrase uses 연애, relating to dating. The fictional character’s name uses 사랑, meaning love.

The ideas are connected, but the Korean words aren’t interchangeable in every context.

For more about Love Cell’s special role in the story, see What Is a Prime Cell in Yumi’s Cells?.

The Future Version of Yourself

Lee also mentioned the familiar habit of imagining that a future version of yourself will handle a task you don’t want to do now.

It’s a relatable joke about procrastination.

Today’s self would rather rest. Next week’s self is apparently going to be wonderfully productive.

Of course, next week’s self may have other ideas.

This kind of expression already treats one person’s competing impulses as though they belong to different characters.

That is close to the basic comic logic of Yumi’s Cells.

A decision that looks simple from the outside can involve a disagreement on the inside.

The creative leap is turning that disagreement into something the reader can see.

This doesn’t mean the cells should be understood as an accurate model of psychology. Lee was drawing on everyday ways of talking about feelings, not presenting a scientific theory of the brain.

And these jokes aren’t exclusively Korean human experiences.

What makes the Korean-language background interesting is that Lee identified expressions from his own linguistic environment as material he could develop into a comic.

Why Did Lee Choose Such an Ordinary Main Character?

Yumi doesn’t need supernatural powers or a dangerous fantasy world to experience a meaningful conflict.

She has work, relationships, uncertainties, and decisions that don’t always come with obvious answers.

In his Korea.net interview, Lee explained that ordinary characters can be especially easy for readers to relate to and support.

The idea is simple but important.

A spectacular character may be fascinating to watch. An ordinary character can make it easier to recognize something of yourself in the story.

That doesn’t mean every reader will share Yumi’s experiences.

Her circumstances are specific to her fictional life.

But small moments of uncertainty, embarrassment, excitement, or hesitation don’t require elaborate background knowledge.

Making a Small Moment Feel Important

This is where the cell idea becomes particularly useful.

On the outside, Yumi might be considering what to say to someone.

That is not necessarily a dramatic event.

Inside her mind, however, the same decision can become an argument between characters with competing priorities.

The comic can give a brief everyday interaction the structure of a larger scene without pretending that the outside world has become extraordinary.

That’s part of the appeal of this storytelling approach.

A huge fantasy battle isn’t required. The emotional conflict is already there.

The cells simply give it a visible form.

This is an interpretation of how the device works, grounded in Lee’s comments about ordinary characters and relatable experiences. It isn’t a claim that he planned every scene around a single stated formula.

Making a Webtoon Easy to Read Isn’t the Same as Making It Carelessly

Lee has also discussed the kind of reading experience he wanted to create.

In a 2019 WebtoonGuide interview, he emphasized simplicity and accessibility.

He described wanting comics that people could follow in everyday situations, including while traveling on a moving bus.

He also valued the possibility of understanding the broad situation without needing to remember every earlier installment.

That’s a revealing production principle for a serialized webtoon.

A reader may encounter an episode during a commute, between other activities, or after missing some of the previous installments.

A story built around recognizable situations and easily identifiable characters can welcome that kind of reading.

Why the Cells Help With Readability

The cells offer a visual shorthand.

Instead of repeatedly explaining in narration that Yumi is anxious, conflicted, hungry, or trying to think rationally, the comic can give those competing reactions individual presences.

Once a reader becomes familiar with the characters, their involvement can communicate a great deal very quickly.

That’s not the same as saying the creator never needed dialogue or exposition.

It means the artwork and character concept can carry some of the explanatory work.

There is another distinction worth keeping in mind.

A comic that feels effortless to read may still require considerable effort to make.

In an earlier interview published by JoongAng Ilbo, Lee discussed how few installments had come easily to him during the comic’s early years.

That makes his emphasis on simple, accessible storytelling more meaningful.

Ease for the reader was an artistic goal, not evidence that the work itself was simple to produce.

Why Yumi’s Cells Is About More Than Romance

Romantic relationships are central to much of Yumi’s Cells, but Lee has been clear that human emotion is the larger subject.

In a February 2026 interview with Hankook Ilbo, he discussed wanting to explore feelings in depth rather than limiting his work to romance alone.

Romantic experiences provide many opportunities for emotions to become particularly intense.

But the emotions themselves aren’t exclusive to dating.

Uncertainty, disappointment, hope, embarrassment, affection, and the desire to understand another person can appear throughout everyday life.

Lee also discussed focusing on experiences that readers of different genders could recognize.

That gives useful context to the series’ appeal.

Yumi is a specific fictional woman, not a character who represents every Korean woman. Her experiences aren’t a universal account of how Korean people think about relationships.

At the same time, a story about one person’s inner life can offer moments that feel familiar to readers whose lives are very different from hers.

The Cells Make Feelings Playful Without Making Them Meaningless

There’s an interesting balance in the concept.

A small cartoon character arguing about what to do can be funny.

Yet the emotion behind that argument may be important to the person experiencing it.

The visual joke and the emotional situation don’t cancel each other out.

Instead, the playful presentation can make an uncomfortable or complicated feeling easier to approach.

This helps explain why the webtoon’s concept has more lasting potential than a collection of cute mascots.

The cells have something to do.

They give ordinary emotional experiences a dramatic form.

How Involved Was Donggeon Lee in the K-Drama Adaptation?

The original webtoon later became a Korean television drama combining live-action performances with animated cells.

But the existence of an adaptation doesn’t mean the original creator personally controlled every production decision.

In his 2023 Korea.net interview, Lee described the television adaptation as a separate creative undertaking.

He said he answered questions about the story’s early setup but otherwise left the production team’s creative work to them.

He also recognized that the drama’s changes could have strengths of their own.

That’s useful context for international viewers who discover Yumi’s Cells through the television series.

The original cells were created as drawn comic characters. The drama developed a new presentation involving animation, acting, and voice performances.

The same underlying idea moved into a different creative process.

For a closer look at those format differences, see Yumi’s Cells Webtoon vs. K-Drama: 5 Adaptation Differences That Matter.

This creator background doesn’t establish which adaptation is better. It simply clarifies the different responsibilities involved.

What the Creator’s Interviews Help Us Understand

It’s tempting to look for one dramatic moment when a successful story was invented.

The history of Yumi’s Cells suggests a less tidy—and more interesting—creative process.

Lee’s stationery designs helped shape his early character drawing.

Familiar expressions about romance and procrastination offered material for imagining little personalities behind human decisions.

His interest in ordinary experiences helped determine the kind of character and story those cells would serve.

And his attention to simplicity influenced how he wanted people to read the finished comic.

These ideas connect, but they aren’t identical.

The design background explains something about the look.

The everyday language helps explain the central device.

The interest in ordinary people helps explain the subject matter.

The emphasis on accessibility helps explain the storytelling approach.

None of these facts means every artistic decision can be traced to a single interview answer.

They do, however, show why the work’s unusual concept feels closely connected to everyday life.

Final Takeaway: An Everyday Thought Became a Storytelling World

Yumi’s Cells didn’t need an extraordinary hero or an unfamiliar fantasy kingdom to find room for imagination.

Donggeon Lee took recognizable thoughts and feelings, gave them small expressive characters, and used them to make ordinary moments more visible.

His interviews reveal how several different creative influences came together: stationery illustration, familiar Korean expressions, accessible comic storytelling, and an interest in people whose lives readers could recognize.

The result is a webtoon where the smallest internal disagreement can become an entire scene.

That’s the particularly clever part of the cell idea: it doesn’t make ordinary emotions important by turning them into something else. It makes visible how much is already happening beneath an ordinary moment.

For an introduction to the original webtoon, its Korean title, official reading editions, and screen adaptations, visit the Yumi’s Cells title guide.

If you’d like to start reading, the official English Yumi’s Cells WEBTOON is the licensed digital comic.

Official Sources and Creator Interviews

• Korea.net — Interview With Donggeon Lee (2023) — creator’s stationery background, rounded drawings, everyday expressions, ordinary protagonists, and approach to the drama adaptation.
• WebtoonGuide — Donggeon Lee Interview (2019) — creator’s thoughts on accessible comic storytelling, character expression, and working methods.
• Hankook Ilbo — Donggeon Lee Interview (February 2026) — creator’s comments on everyday emotions, romance, and reaching readers across genders.
• Korea JoongAng Daily — Donggeon Lee Interview (2018) — early reporting on the comic’s development and the work involved in creating episodes.
• Naver WEBTOON — 유미의 세포들 — original Korean publication, creator, and episode catalog.
• WEBTOON — Yumi’s Cells — official English comic and original creator credits.